Sandbagging is used in flood control, temporary construction and military applications. It remains the most cost-effective and efficient method of flood control and military construction to date. Millions of sandbags are used for flood control when river banks overflow. In military installations, such as those encountered in Vietnam, up to thirty million sandbags a month were utilized. All of these were filled by hand. The small size of the sandbag (seventeen by ten by four inches), makes its carrying and positioning a one man operation. When sandbags are used as a single unit of many, the size allows great flexibility for building earth works. The use of sandbags is comparable to that of brick. It can be used in a variety of positions and numbers to create unlimited and differing results. Once the sandbags are set, they can be easily removed and repositioned as required.
Until the 1960's, the bags were made of burlap, folded, and sewn on two sides, with a drawstring in the third side. By the 1970's, a woven polypropylene replaced the burlap, and technical innovation in bags came to a halt. Currently, bags are woven, folded, and sewn at a remote facility, after which they are shipped to the site and filled. In most instances, the sandbags are filled strictly through manual labor. A person fills them with a few shovels full of soil or sand, pulls and ties the drawstring, and tosses the completed bag into a pile to be picked up at a later time.
Sandbags are often the only flood control method available to reinforce or raise the height of dikes, berms, or levees used to protect property from flood water damage. The typical method used to fill sandbags is that one person holds the sandbag while a second person shovels sand or other granular material into the bag. When the bag is filled and the open end of the bag closed, the sandbag is ready for use. This method requires two people to fill a single sandbag at a time when there are generally insufficient personnel available to complete the work required to prevent or minimize flood damage. Additionally, as much as fifty percent of the sand thrown at a sandbag misses the bag, and falls back to the ground. The sand that misses the bag results in wasted effort. Thus, it takes a longer period of time to fill a sandbag and more energy is expended per sandbag. Consequently, fewer sandbags are filled in a given time period.